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async_hooks: simplify fatalError #14051

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async_hooks: simplify fatalError #14051

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17aafd7
async_hooks: simplify fatalError
AndreasMadsen Jul 3, 2017
278b163
[squash] use try finally, for better stack traces
AndreasMadsen Jul 3, 2017
610d365
[squash] ensure that uncaughtException listeners are removed
AndreasMadsen Jul 3, 2017
1d3f69b
[squash] async_hooks c++ already have a try finally for each hook
AndreasMadsen Jul 3, 2017
527a4f6
[squash] add frindly comment explaining _events interaction
AndreasMadsen Jul 3, 2017
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46 changes: 24 additions & 22 deletions lib/async_hooks.js
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Original file line number Diff line number Diff line change
Expand Up @@ -60,19 +60,11 @@ async_wrap.setupHooks({ init,
destroy: emitDestroyN });

// Used to fatally abort the process if a callback throws.
function fatalError(e) {
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@refack refack Jul 3, 2017 •
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Why is everyone trying to kill this 😨
I like it as a way to bail from a callback or a Promise.catch
Ref: #13839 (comment)

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Just because it is useful for Promise.catch doesn't mean that is useful here.

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Probably. I'll copy it to test/common/

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Letting an error bubble with try {} finally {} have always been the standard way of handling throws.

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Except what async_hooks is doing isn't standard. This is a guard to prevent an abort from C++ if it detects stack corruption that can likely result from the user try catching/Promise wrapping the call, and to get useful core dumps. It also doesn't follow how this is handled in C++ (https://github.com/nodejs/node/blob/v8.1.3/src/env-inl.h#L144-L160). I'm a big -1 on this.

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By "exporting FatalException" do you mean expose it to JS?

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@trevnorris trevnorris Jul 3, 2017 •
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If anything I'd like to export the code in Environment::AsyncHooks::pop_ids() and use that as the uniform way to exit the process.

EDIT: Except it should show a JS stack instead of a C++ stack.

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By "exporting FatalException" do you mean expose it to JS?

Yes. At the very least I would like a unified way of making a fatal exception. Currently, there are a couple of different implementations floating around in nodecore. It makes things like --abort-on-uncaught-exception difficult to test.

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@AndreasMadsen

At the very least I would like a unified way of making a fatal exception.

Sounds good to me.

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So area this is currently a WIP?

if (typeof e.stack === 'string') {
process._rawDebug(e.stack);
} else {
const o = { message: e };
Error.captureStackTrace(o, fatalError);
process._rawDebug(o.stack);
}
if (process.execArgv.some(
(e) => /^--abort[_-]on[_-]uncaught[_-]exception$/.test(e))) {
process.abort();
}
process.exit(1);
// This is JavaScript version of the ClearFatalExceptionHandlers function
// in C++.
function clearFatalExceptionHandlers(e) {
process.domain = undefined;
process._events.uncaughtException = undefined;
}


Expand Down Expand Up @@ -345,15 +337,17 @@ function emitInitS(asyncId, type, triggerAsyncId, resource) {

function emitBeforeN(asyncId) {
processing_hook = true;
var didThrow = true;
// Use a single try/catch for all hook to avoid setting up one per iteration.
try {
for (var i = 0; i < active_hooks_array.length; i++) {
if (typeof active_hooks_array[i][before_symbol] === 'function') {
active_hooks_array[i][before_symbol](asyncId);
}
}
} catch (e) {
fatalError(e);
didThrow = false;
} finally {
if (didThrow) clearFatalExceptionHandlers();
}
processing_hook = false;

Expand All @@ -371,8 +365,11 @@ function emitBeforeS(asyncId, triggerAsyncId = asyncId) {

// Validate the ids.
if (asyncId < 0 || triggerAsyncId < 0) {
fatalError('before(): asyncId or triggerAsyncId is less than zero ' +
`(asyncId: ${asyncId}, triggerAsyncId: ${triggerAsyncId})`);
clearFatalExceptionHandlers();
throw new Error(
'before(): asyncId or triggerAsyncId is less than zero ' +
`(asyncId: ${asyncId}, triggerAsyncId: ${triggerAsyncId})`
);
}

pushAsyncIds(asyncId, triggerAsyncId);
Expand All @@ -387,15 +384,17 @@ function emitBeforeS(asyncId, triggerAsyncId = asyncId) {
// this is called.
function emitAfterN(asyncId) {
processing_hook = true;
var didThrow = true;
// Use a single try/catch for all hook to avoid setting up one per iteration.
try {
for (var i = 0; i < active_hooks_array.length; i++) {
if (typeof active_hooks_array[i][after_symbol] === 'function') {
active_hooks_array[i][after_symbol](asyncId);
}
}
didThrow = false;
} catch (e) {
fatalError(e);
if (didThrow) clearFatalExceptionHandlers();
}
processing_hook = false;

Expand Down Expand Up @@ -427,15 +426,17 @@ function emitDestroyS(asyncId) {

function emitDestroyN(asyncId) {
processing_hook = true;
var didThrow = true;
// Use a single try/catch for all hook to avoid setting up one per iteration.
try {
for (var i = 0; i < active_hooks_array.length; i++) {
if (typeof active_hooks_array[i][destroy_symbol] === 'function') {
active_hooks_array[i][destroy_symbol](asyncId);
}
}
} catch (e) {
fatalError(e);
didThrow = false;
} finally {
if (didThrow) clearFatalExceptionHandlers();
}
processing_hook = false;

Expand All @@ -460,6 +461,7 @@ function emitDestroyN(asyncId) {
// exceptions.
function init(asyncId, type, triggerAsyncId, resource) {
processing_hook = true;
var didThrow = true;
// Use a single try/catch for all hook to avoid setting up one per iteration.
try {
for (var i = 0; i < active_hooks_array.length; i++) {
Expand All @@ -470,8 +472,8 @@ function init(asyncId, type, triggerAsyncId, resource) {
);
}
}
} catch (e) {
fatalError(e);
} finally {
if (didThrow) clearFatalExceptionHandlers();
}
processing_hook = false;
}
Expand Down
10 changes: 7 additions & 3 deletions test/async-hooks/test-callback-error.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,10 @@ const async_hooks = require('async_hooks');
const initHooks = require('./init-hooks');

const arg = process.argv[2];
if (arg) {
process.on('uncaughtException', common.mustNotCall());
}

switch (arg) {
case 'test_init_callback':
initHooks({
Expand Down Expand Up @@ -50,7 +54,7 @@ assert.ok(!arg);
console.time('end case 1');
const child = spawnSync(process.execPath, [__filename, 'test_init_callback']);
assert.ifError(child.error);
const test_init_first_line = child.stderr.toString().split(/[\r\n]+/g)[0];
const test_init_first_line = child.stderr.toString().split(/[\r\n]+/g)[3];
assert.strictEqual(test_init_first_line, 'Error: test_init_callback');
assert.strictEqual(child.status, 1);
console.timeEnd('end case 1');
Expand All @@ -61,7 +65,7 @@ assert.ok(!arg);
console.time('end case 2');
const child = spawnSync(process.execPath, [__filename, 'test_callback']);
assert.ifError(child.error);
const test_callback_first_line = child.stderr.toString().split(/[\r\n]+/g)[0];
const test_callback_first_line = child.stderr.toString().split(/[\r\n]+/g)[3];
assert.strictEqual(test_callback_first_line, 'Error: test_callback');
assert.strictEqual(child.status, 1);
console.timeEnd('end case 2');
Expand Down Expand Up @@ -115,6 +119,6 @@ assert.ok(!arg);
assert.strictEqual(stdout, '');
const firstLineStderr = stderr.split(/[\r\n]+/g)[0].trim();
assert.strictEqual(firstLineStderr, 'Error: test_callback_abort');
console.timeEnd('end case 3');
});
console.timeEnd('end case 3');
}
4 changes: 2 additions & 2 deletions test/async-hooks/test-emit-before-after.js
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Original file line number Diff line number Diff line change
Expand Up @@ -16,13 +16,13 @@ switch (process.argv[2]) {
}

const c1 = spawnSync(process.execPath, [__filename, 'test_invalid_async_id']);
assert.strictEqual(c1.stderr.toString().split(/[\r\n]+/g)[0],
assert.strictEqual(c1.stderr.toString().split(/[\r\n]+/g)[3],
'Error: before(): asyncId or triggerAsyncId is less than ' +
'zero (asyncId: -1, triggerAsyncId: -1)');
assert.strictEqual(c1.status, 1);

const c2 = spawnSync(process.execPath, [__filename, 'test_invalid_trigger_id']);
assert.strictEqual(c2.stderr.toString().split(/[\r\n]+/g)[0],
assert.strictEqual(c2.stderr.toString().split(/[\r\n]+/g)[3],
'Error: before(): asyncId or triggerAsyncId is less than ' +
'zero (asyncId: 1, triggerAsyncId: -1)');
assert.strictEqual(c2.status, 1);
Expand Down